Process for the production of gas, oil, and other products



March 13, 19341. L. (2. KARRECK PROCES S FOR THE PRODUCTION OF GAS; OIL,AND OTHER PRODUCTS Filed Oct. 29. 1926 ATTORNEYfi Patented Mar. 13, 1934UNITED STATES PATENT OFFlC Lewis Cass Kai-rick, Salt Lake City, UtahApplication October 29,

3 Claims.

This invention relates to processes for the production of gas, tar-oils,coke, and other products from coal and other carbonaceous material andis herein illustrated as applied in a" plant for ob- 5 taining theseproducts from coal. The solid raw material is reduced to a granular orpulverized condition, such as will permit it to be conveyed through aheated tube by a current of steam or other gas or vapor acting as-acarrier for the material and as an atmosphere surrounding it whilesubjected to heat, suitable for yielding the desired products. Theprocess may be used in treating the fine coal composing parts ofshipments received at power plants, the coarser sizes or dust beingsubjected to other treatments or gasification which inventions formdivisions of the present application. This development provides foreconomical use of steam as the principal heat-transferring agent andpermits the grades of coal as received to be subjected to the type oftreatment for which they are best adapted.

To carry out economically the features of this process, the fine coalmay be treated with. superheated steam to yield tar-oils, resins, waxes,gas and fine low-temperature coke. The condensation of these productsand the steam gives a large supply of heat which may be utilized for theproduction of a further supply of steam at a lower pressure. Thisfurther supply of steam may be superheated in the formof the inventionherein disclosed in distilling a further amount of coal or it may bedisposed of advantageously in the other processes.

According to this invention I overcome the operating difficulties ofother processes in obtaining rapid distillation of coals. Thedifliculties are due principally to the fusing properties of the coalsand their poor heatconductivity and I overcome these controlling factorsto such an extent that coals can be distilled very quickly to any degreeof devolatilization regardless of their fusing properties orconductivity of heat, or the grade of coal and amount of mineral mattertherein. The present invention provides for the successful use of culmor slack coal as well as for many other types of carbonaceous materialseven sawdust being utilizable.

In the form of the invention herein illustrated the finely dividedcarbonaceous material, such as coal which has preferably been preheated,is introduced into an externally heated pipe carrying a stream of steam.When the carbonaceous material is of the fusing type, air also may beintroduced advantageously, or the coal dust may be subjected to apre-treatment with air or combus- 1926, Serial No. 144,947

tion gases in the same type of apparatus. To distill the tar-oils andobtain only part of the total possible gas, from the coal, the stream ofsteam and air, if added, is heated to a temperature well within thetemperature range of low temperature 80 carbonization which will preventexcessive cracking of the tar-oils. Too high a temperature must not beused because the coke formed in the process will react with the steam toform water gas and the tar-oils will be decomposed largely into gasesand heavy tars of poor quality. I have used temperatures from 700 F. to1200 F. satisfactorily.

The finely divided carbonaceous material presents an immense amount ofsurface to react with the steam and to take up the heat thereof, makingit possible to obtain substantially complete gasification of thecarbonaceous materials present with great rapidity. Coal carried insteam of high velocity, say 100 to 600 feet per second, in a. one-inchpipe 100 feet long has been found sufficiently reactive under the aboveconditions to complete the gas-forming reactions. Under the conditionsdescribed below the turbulent flow of the steam and its contact with theheat-transmitting walls of the apparatus have accomplished veryefiicient transfer of heat from the combustion gases surrounding thepipe to the rapidly moving steam and to the fine carbonaceous materialinside the pipe. Under these conditions the reaction appears to bepractically a surface one between the steam and the carbonaceousmaterial. It also appears that either the reaction is almostinstantaneous by which the particles are consumed, or, there is rapiddisintegration of the carbonaceous particles by the wear to which theyare subjected in the pipe and the carbon dust is then reacted upon moreeflicaciously because of the much greater reacting surface provided.

I have used one form of this process for distilling finely divided coalat low temperatures for the production of coal gas, and obtained a largeyield of rich gas and tar oils and a low-temperature coke dust which waseasily ignitible and suited for power plant use. In carrying out theprocess, the preheated coal was placed in a pressure chamber ormagazine, hereinafter described, and then was .fed by a suitable screwdevice into the upper end of a one-inch pipe coiled around a verticalaxis and carrying steam. The steam carried the coal down through thecoil and hot combustion gases surrounding the coil, heated the stream ofsteam and coal so as to distill the combustible volatiles from the coal.To effect this result the temperature within the pipe was kept above 700F. and below 1200 F. The prod- 110 ucts passed out of the lower, hottestpart of the coil and entered a hot walled or heat-insulated cyclone dustcollector which precipitated most of the coke and ash and permitted thevolatile products to pass on to the condenser.

Clogging of the pipes by any adhering coal was found to be entirelyprevented by dropping pieces of iron such as small metal punchings intothe pipe ahead of the coal injector. These effectively removed anyadhering coal and also prevented scale from forming. The pieces of ironwere easily separated from the volatilized coke residues and could bereturned by mechanical devices for reuse.

The latent heat released by condensing the volatiles from the aboveprocess is shown in the present disclosure as conserved or re-used inproducing a second supply of steam which is used for the completegasification of carbonaceous particles so that the products of thissecond steam treatment may be used for distilling coarse coal. The newsteam from the first unit may, of course, be used in a second similarunit for distilling coal.

One of the economies resulting from the present invention is obtained byoperating the above described carbonization and gasification processunder suitable pressure so that the volatiles produced, together withany undecomposed steam, and oil vapors may be made to give up theirsensible and latent heats to produce fresh steam at a lower pressure tobe used in a succeeding unit operating at a lower pressure.

The accompanying drawing which is an elevation with parts in verticalsection shows diagrammatically an apparatus for carrying out theprocess.

In the form of the invention here shown steam is used for distillationof coal in one retort, shown as a coil, the resulting vapors and gasesare cooled in a heat exchange device and the fresh steam at lowerpressure thus obtained is used with further additional heat tocompletely gasify other coal or coke in a similar retort. The hotgaseous products from this second lot of coal are shown as heating aretort through which sized coal is fed to produce low-temperature coke,a rich gas, and to obtain the condensible volatiles from it.

The coiled -pipe device for gasification was found to worksatisfactorily with one inch pipe of uniform diameter, so that the speedof the steam, owing to its increased volume on high temperatures, isincreased as it flows through the pipe. Using dry steam at about 25pounds pressure at a temperature of about 265 F. the volume would bedouble in rising to 1000" F. and treble in rising to 1700" F. Theapparatus was found to work satisfactorily under these and otherconditions.

The pulverized fuel gasifler furnace 1 shown, consists of aheat-insulated outer wall 2, inside of which is a cylindrical centerwall or core 3 having a pipe coil 4 supported in the annular space 5between the wall and the core.

Steam from a boiler or other source such as an evaporator enters thesystem 6 and passes through the steam trap 7 and valve 8 where the steamis throttled down to any desired pressure before passing into the coil4. The steam passes down through the coil 4 to an exit 9 movingcountercurrent to the combustion gases which ascend rapidly in theannular space 5. The required heat is supplied by the combustion ofgases in the annular checkerwork 10, the gas and air be ing introducedby burners 11 at the bottom of the gasifier 1. The combustion gases passout of the furnace 1 through the stack 12 which also serves as a drierand preheater for the pulverized material such as coal which is to bedistilled; The pulverized material is charged into the feed bin 13 inthe center of the stack 12 through the magazine 14 which with its topand bottom valves 15 and 16 serves as a lock or means of keeping the binfull at all times while preventing steam from flowing up through the bin13. The bottom of the feed bin contains a power driven screw-feed 17having a speed regulating device 18 by which the dry and preheatedmaterial can be charged continuously at any rate in the steamline 19entering the top' of the gasifier 1. Pieces of iron which are used toscour the inside walls of the coil 4 may be fed at intervals into thesteam line 19 from the valve-closed hopper 20 by means of a suitablefeeding device such as a power driven crank and slide valve 21 whichcontains an aperture to receive one device or more at a stroke.

The exit gases carrying whatever there is of ash and the coke passthrough the exit 9 and through the conduit 22 to the dust collector 23,which may be a suitable type of cyclone dust collector and is preferablywell protected by heat in- 100 sulation so that there is no separationof condensible vapors here. The solids may be withdrawn from thecollector into a double-valved bottom bin 24 without material loss ofgas or pressure.

The cleaned gases and vapors pass on through a conduit 25 to a. coil orother cooling element 26 forming part of a heat exchange device whichalso serves as an evaporator. The pressure and therefore the temperatureof the vapors in the 110 conduit 25 will be so high that the water inthedevice 26 yields the steam usedin a second coal heating device whilethe condenser vapors of water and tar, oils, resins, and so forth,together with uncondensed gases flow out of the coil 27 by 115 a main 28into a separator 29 without material reduction in pressure.

In this it is found that four products separate when a coal such as Utahcoal is used. The heaviest of these products is a layer of resinscarrying wax, which is a sticky viscous mixture when cold, and which canbe drawn off by a bottom valve 30. Above this lies a much deeper layerof water carrying principally ammonia and some tar acids which can bedrawn off by a valve 31, Above the water floats a layer of oil and waxwhich when cold is of the consistency of cup grease and can be drawn offby a valve 32. Above the oil layer is a space which is occupied by theuncondensible gases carrying some light oil which 30 may be removed in ascrubber and which can be drawn off through a valve 33.

The steam generated in the heat exchange device 26 from the latentandsensible heats of condensed vapors, gases and water may be used 5 fordistilling a further quantity of coal in a second unit similar to theone already described The invention may also be used for thecarbonization of lump coal by the sensible heat of hot gaseous productsobtained from the treatment of 140 finely divided coal in one of theunits mentioned above. I thus apply the invention by the gasification ofcoal with the utilization of the sensible heat of the vapors and gasesthus produced for the low temperature carbonization of a second quantityof coal which is preferably lump coal, thus providing for the completeutilization of all forms of the coal received by an ordinary commercialplant.

For this purpose the steam generated in the 150 heat exchange device 26is carried by a valved heat-insulated main 34 through a steam trap 35and past a valve 37 to gasirying coil 38 into which pulverized coal isintroduced as into the coil 4. The coil 38 like the coil 4 lies in anannular space 39 between the heat-insulating outer wall 40 and the core41. The coil 38 like the coil 4 is heated by burners 42 at the bottom soas to heat the lower part of the coil to the highest temperature whilethe products of combustion rise around the upper part of the coil andpas oil through a stack as which, like the stack 12, surrounds a feedbin 4e fed by a magazine 45 similar to the magazine is. There may alsohe provided a variable coal feeding device 46, and a variable feedingdevice 47 for feeding pieces of iron or other solid materials formaintaining the coil 38 free from carbon and scale on its inner surface.

The exit end as of the coil passes into a cyclone heat-insulated dustcollector 49, similar to the dust collector 23, which removes the hotsolids from the gas and vapor stream. There is provided a double-valvedbottom bin 5G for removing the solids collected in the dust collectoris.

The heat insulated outlet pipe 51 of the dust collector d9 conducts thestill very hot products of gasification into a retort diagrammaticallyshown at 52 where the gases are used to carhonize coal or othermaterial. The retort may he thirty or more feet high and steam may befed to it from number of coils 38. 'l'ne properly sized coal preferablyfree from fines, is fed into the tapered upper part 53 of the retort bya valved opening cc. To enable the coal to be preheated it comes from avalve-closed loin provided with heating means described below. Forheating the coal in the retort by such ases as come from the main 51 twoprocedures have been found useful. According to one procedure thedescending coal is heated by a counter-current up-ilow of steam and 4gas. The principal heat may be supplied by the hot gases coming from themin 51. To efiect this an annular manifold 55 surrounds the retort 52 atthe large bottom end or tapered portion 53 and throtgh this the hotfluid gas and vapors coming from the main 51 are led by a valvedconnection 57.

The entering gases will he about 1204? F. to 1859" F. and will distillon the volatiles in the coal with great rapidity while the steam reactsto a considerable extent the resulting coke and icy increasing the rateof flow of the coal so that it carries volatile oil ingredients intosteam hot enough to crack them, the reacts with the carbon particlesreleased by the cracking and forms water gas and gaseous and condensihlelight hydrocarbons. The volatile products and gases pass upwardlythrough the coal and pass out or" a manifold 58 below the openingPreferably there is a column oi coal between manifold 58 and theopening" 54 enough to provide a continuous supply of coal to the dissomewhile valve 5c is closed and the 55 is being recharged. The coal may bepreheated by passing part of the highly heated from the 551 through avalved insulated pip-e into the bin 55. The gases pass down through thematerial in the loin 55 and out or" the system at the manifold 58thereby and preheating the coal and simultaneously serving the valuablefunctions of zz reventing tar and oil vegoors from the distilling coalfrom entering the bin 55 and.

condensing there. The gases and vapors leaving icy the manifold 58 entera heat hisulated and valved main 80 which conveys them to a heat in=main to to a suitable source of coke discharged.

sulated cyclone dust collector 61 where the dust is removed. From this aheat insulated main 62 carries the vapors and gases almost at issuingtemperature to an evaporator or heat exchange device 63 which may helike the device 26. Here the latent and sensible heat of condensiblematerlals are recovered and the four products, resin,

water, oil and gas, are separated in a separator 6t like the separator29 and removed as desired by valves 65, 66, 67 and 68. I

In addition to the heat provided at the manii'old 56 the contents of theretort are further heated by steam rising from the residues or from thecoke formed. Ihe lower part 70 of the retort may be cylindrical orstraight instead of tonering. It may terminate in one of the customaryforms having an elbow 71 forming a nearly horizontal support for theload of the charge in the retort. The feed of the contents past theelbow 71 may be controlled by arms '72, fast on a rotatable shaft 73which may be rotated by any suitable means, and exiend toward pivotedhanging arms is which detain the upper part of the charge at the nearlyhorizontal section 71. After pessing the elbow or horizontal portion 71the residues or coke drop into a bottom bin '35 and rest on theclosedbottom valve 76 thereof. A valve 77 leetween the bin 75 and lowerpart of the retort may be closed when it is desired to remove thecontents of the bin 75 which requires the opening of the valve 76. Theresidues of coke lying upon the valves 76 and 77 can be or steam whichmay he provided by introducing the necessary gas, vapor, water or steamthrough valved pipes 78 and vs which are connected by a steam 81. Thesteam or other material introduced at 78 and ?9 may be laden withadmixed solutions of lightgiving salts or odoriierous materials, thusenabling any desired properties to be given to the The heat of the cokeor resi-- dues lying upon the valves 7-8 or 77 sunerheats the steam orvapors so that they aid in heating the charge in the retort thusrecovering a very large proportion of the heat usually lost inceroonizing processes.

The second procedure winch has been found useful for heating the chargein the upper part 58 of the retort, is to close the valved connection 5?and open a valve 32 at the upper manifold 58 thus admitting steam fromthe main .51 to the ringer manifold. The valve 33 in the 60 is alsoclosed, and a valve fi l in a branch of the main Gil and extending tothe lower manifold.

56 is also open-ed with the result that heating i steam and vapors from.the main .51 enter the top of the retortand flow with the charge of coalto the manifold 5-9 and then oil to the branch 85 in the dust collector=81. It found that rather more is obtained a charge heated according tothe latter ethod than is obtained charge and the retort is heated by acounter=ciurent new of steam and vapor.

in order to preheat in the 55 steam may he dravm either from a steam 8ior from. the steam vanor main 51. There is provided in the main toleadiog from. the ill a valve :86 which may be open to allow steam toflew up an extension 8? into the bin 55. he an alternative method ofheating the bin 55 the valve @8 oi the extension 59 or the til may heopened. Either of these methods oi heating the 55 serves to keep var-oreand from con- Elli/ll used to heat gas, water fi m 4- densing in the bin55 as they arise from the upper part of the retort 53. V

The evaporators 26 and 63 are provided with valved cold water inlets 89at their bottoms. The oils condensed by the cold water are easilyseparated into portions which contain a large proportion of variousproducts. The amount and character of these products varies with thematerial treated. To obtain the above described separation without anyseparate operations for separating the materials the separators mayconsist of long, narrow, closed chambers in which the condensed materialmoves toward the outlet very slowly, with the result that stratificationis effected as the streams approach the decanting valves. The gasesleaving the separators are usually scrubbed to remove uncondensed lightoils and ammonia.

It will be seen that the apparatus shown is one in which successivegasifiers work efliciently at successively lower pressures, thus oneutilizes the latent heat and the sensible heat of steam, gases andsuperheated vapors from the preceding one, generating from 50% to 75% byweight as much steam as the weight of material so condensed. It hasbeenfound that when complete gasiflcation temperatures are used very littlecoke collects in the dust collectors 23 and 49. For the convenience ofoperating the apparatus, steam gages are placed on each evaporator andat the outlet to each coil.

In one low pressure test run substantially saturated steam was'used at apressure approximating six pounds per square inch and into this was fedcoal, all passing l6-mesh and averaging rather smaller than 40-mesh atthe rate of about a half pound of coal per pound of steam, the steamflowing at the rate of about .85 pounds per minute. The coil of one-inchpipe about feet long was heated at the lower end by gases having atemperature of approximately 1830 F. and the steam as it passed throughthe coil increased in temperature from the admission end where it. was230 F. to about 1600 F. Gas was produced in excess of the capacity ofthe meter to measure and substantially all the coal was gasified.

It was found that powdered low temperature coke from Utah coal insteadof coal, gave a flow of gas which could be controlled instantly byvarying the temperature or fiow of steam or amount of coke dustsupplied, so that the process was well adapted to produce gas forarapidly varying demand. The ash did not clinker and the small amount ofcoal too coarse to completely gasify .was swept out of the coil bysteam. In other runs saturated steam was successfully used at ten and attwenty-five pounds pressure delivering about 1.5 pounds and 2.5 poundsof steam per minute respectively. Varying amounts of coal and coke wereused.

Where substantial steam pressures are used they accelerate the water-gasreaction and also permit steam to be regenerated from the heat evolvedin the condensation of undecomposed steam and from the vapors from onechargeas well as from the sensible heat of the gases formed, and therebyanother charge may be distilled by the fresh steam. The gas formed isrich in ammonia since the best conditions exist for the conversion ofnitrogen compounds of the coal delivering 1.5 pounds of steam per minuteand the combustion gases in contact with the heated coil were at 1750 F.the steam reached the exit end at 1480 F. and when the combustion gaseswere at 2000 F. tlaisteam issued at 1800 F.

What is claimedis:

l. The process which consists inv carrying finely dividedsolid-"carb0nizable material admixed with coke in a high speed stream ofheated steam to separate the volatile part of said carbonaceous materialfrom the solids, condensing the steam and the condensible volatiles,generating new steam from the latent heat of the condensing 100materials, and treating solid carbonizable material with the new steam.

2. The process which consists in introducing finely divided solidcarbonizable material into a stream of steam, superheating the steam toa temperature in excess of 700 F., carrying the steam and gas producedinto heat exchange relationship with a body of water to produce newsteam at a lower pressure and then conducting the same from the place ofproduction as a stream of steam, introducing finely divided solidcarbonizable material into the stream of new steam, heating the streamwith the finely divided carbonizable material contained therein toproduce gas, carrying the hot gas produced through a. retort tocarbonize other solid carbonizable material, and separatingthe gasproduced from the other products.

3. The process which consists in introducing finely divided solidcarbonizable material into a 2 stream of steam, superheating the steamto a temperature in excess of 700 F., carrying the steam and gasproduced into heat exchange relationship with a body of water to producenew steam at a lower pressure and then conducting the same from theplace of production as a stream of steam, introducing finely dividedsolid carbonizable material into the stream of new steam, heating thestream with the finely divided carbonizable material contained thereinto produce gas, carrying the steam and the gas produced through a chargeof coarse coal in a retort to carbonize the coal, separating the gasproduced from the coke and other products, and effecting absorption ofheat from the coke by fluid to be passed into said exchange relation tothe coarse coal.

LEWIS CASS KARRICK.

